1. Field of the Invention
The present invention relates to primer coating compositions exhibiting very good adhesion properties on a large variety of substrates, in particular plastic substrates such as ophthalmic lenses made of organic glasses, and which also impart good impact resistance properties to the thus coated substrates.
The present invention also concerns substrates coated with these primer coating compositions as well as a method for making such coated substrates
2. Previous Art
It is known to apply epoxy/acrylate based primer coating compositions on transparent substrates such as ophthalmic lenses.
Thus, Japanese patent JP 7-35902 discloses coating polyurethane lenses (MR6, with, successively, an epoxy/acrylate primer composition, an anti-abrasive silicone based coating and an anti-reflecting multiplayer coating. The resulting final lenses show good impact and abrasion resistances, good resistance to weathering, a good visual appearance, some colorability and a good adhesion between the layers. The epoxy/acrylate composition comprises acryl esters with OH groups, in particular of the bisphenol-A type.
Japanese patent JP 6-271788 discloses a primer coating composition comprising a mixture of a monomer bearing 1 to 3 acrylate functionalities and one or more hydroxy groups, a mono- or polyepoxy monomer and an initiator. A silicone based anti-abrasion coating and a multilayer anti-reflecting coating are then successively formed on the primer coating. The substrate is made of mineral glass. The coated substrate shows good impact and abrasion resistances, good resistance to weathering, a good visual appearance, as well as a good adhesion between the layers.
In comparative example 1 the substrate is a lens made of CR39® from PPG.
The coated lenses have good performances with regard to impact resistance and adhesion. However, these primer coatings have not proven to be successfully applicable on a large variety of organic substrates in particular (meth)acrylic or polycarbonate based substrates.
Additionally, due to the hydrophilicity of the acrylic constituent of the composition, the resulting coatings are quite sensitive to humidity
What is needed is a primer coating composition which will provide improved impact resistance properties as well as good adhesion to a large variety of substrates, in particular organic glass substrates, and also to anti-abrasion coatings.